Two-phase homogenizer



Sm. 2Q, wm

s. c. ABRAHAM ET AL TWO--PHASE HOMOGEN I ZER 2 Sheets-Sheet l Filed Fb.1Q, 1968 FIGA'.

A FIGLI.

SW@ 29,' 1970 s. c. ABRAHAM ET AL 353mm TWO-PHASE HOMOGENIZER Filed Feb.1," 1968 2 Sheets-Sheet 2 lA/l/E/VTMS E-pwfpng O. MECK l /W/M UnitedStates Patent O 3,531,050 TWO-PHASE HOMOG'ENIZER Stanley CharlesAbraham, Somerville, Mass., and Edward Otto Moeck, Pierrefonds, Quebec,Canada, assignors to Atomic Energy of Canada Limited, Ottawa, Ontario,Canada, a corporation of Canada Filed Feb. 12, 1968, Ser. No. 704,689Claims priority, application Canada, Apr. 22,- 1967, 988,609 Int. Cl. Bb7/06 U.S. Cl. 239-427-3 2 Claims ABSTRACT OF THE DISCLOSURE A nozzlehaving inner and outer coaxial tubes, the orifices of tubes coaxial toone another such that mixing ta-kes place at interfaces between theorifices. The resulting mixture is substantially homogeneous and uniformin cross-section.

This invention relates to an apparatus for mixing flows of liquid andgas, particularly steam and water.

Within certain types of atomic reactors, for example,

fog cooling reactors, it is desirable to have a coolant streamcomprising a homogeneous mixture of water and steam passing over fuelbundles.

The embodiments of the invention achieve a nozzle which will mix aliquid and a gas and in particular water and steam, into a substantiallyhomogeneous two-phase mixture such that the static pressure gradientacross the mixture iiow is substantially negligible.

The invention therefore contemplates a nozzle for mixing a liquid and agas into a two-phase homogeneous mixture comprising: an inner conduitfor connection with a liquid source, a tubular shroud member spaceddownstream from and coaxial with the inner conduit, and outer conduitsurrounding the inner conduit and the shroud member and defining anannular chamber therewith for connection with a gas source, a spacingmember for spacing the shroud member from the inner conduit, the shroudmember having an unstream end and a downstream end, the downstream endterminating in an outwardly extending apertured flange engaged with theouter conduit, the upstream end having a flared flange extendingoutwardly upstream to direct a portion of a gas flowing in the annularchamber into the shroud member, a nozzle seat disposed in the downstreamend of the inner conduit, the nozzle seat having a plurality of skewedchannels therein to impart angular momentum to a liquid flowingtherethrough, and a movable plug positionable with respect to the nozzleseat for controlling the flow of liquid. The spacing member preferablyincludes a constricting ring for constricting the flow of a fiuidthrough the shroud member.

The invention will now be described by way of example reference beinghad to the accompanying drawings in which:

FIG. 1 is an elevation in cross-section of one embodiment of theinvention;

FIG. 2 is an elevation in cross-section of another embodiment of theinvention;

FIG. 3 is a perspective View of the nozzle seat utilized in theembodiment of FIG. 2; and

FIG. 4 is a top view of the nozzle seat and plug shown in FIG. 2.

Referring to FIG. 1 a nozzle 9 includes an inner conduit and has anextended interior 11 and a flow turn chamber 12 disposed therein. A pipe13 communicates with the chamber 12. to a source of liquid flow (notshown) for example, a water pump. The interior 11 of the conduit 10terminates at an orifice 14 forming a peripheral ICC knife edge 16 suchthat a bevel 17 slopes towards the outside surface 18 of the conduit10'. The opposite end 19 is closed off as by a plate 20.

Surrounding the conduit 10 is an outer conduit 21 defning a chamber 22between it and conduit 10. A plurality of spacers 23 restrain theconduit 21 in coaxial alignment with the conduit 10. Each spacer 23 hasorifices 24 therein to permit communication throughout the chamber 22 aswill be later more clearly understood. A plurality of circumferentialslots 25 through the inner conduit 10, in the vicinity of the bevelededge 17, communicate charnber 22 `with interior 11. A pipe 26communicates with chamber 22. The pipe 26 is adapted to be connected toa source of gas pressure (not shown). The outer conduit 21 terminates atan orifice 2.7 which is coaxial with the orifice 14. The margins oforifices 14 and 27 define coaxially an annular mixing zone 29.

When steam is supplied to pipe 26 and liquid, for example, water, topipe 13 the liquid and gas flow, following the arrows in FIG. 1, throughthe interior 11 and chamber 22 respectively. The gas passes partlythrough slots 25 for partial mixing with the liquid at 18, and partlythrough 29 lwhich lmixes with the aforesaid partially mixed mixtureissuing from orice 14. This mixture issues out orifice 27. This mixingof the liquid and gas phase also takes place in an extended mixing zone30, in the vicinity of zone 29, such that the fluid phase, downstreamfrom orifice 27, is homogeneous in character and has almost no staticpressure gradient at right angles to the flow.

In reality zones 29 and 30 blend into one another such that no cleardemarcation between the two can be made. Throughout the extendedinterior 11, a fuel string 32 (shown in shadow), which consists of aseries of coaxially connected fuel bundles can be placed to extendbeyond the zone 30 and the orifice 27. The nozzle 9 thereby causes ahomogeneous two-phase gas-liquid mixture to iiow over the string 32 inthe region 33 downfiow from zone 30 (and orifice 27) while permitting apure liquid fiow across the fuel string 32 in the interior 11.

Suitable values of the dimensions of the nozzle 9 are given by way ofexample. The distance between the center of pipe 26 and the base 34 ofthe orifice 27 is 16.50 inches; the distance .between the center of pipe26 and that of pipe 13 is 15 inches; the diameter of the interior 11 andof the orifice 27 is 3.250 inches.

Referring to FIG. 2 a nozzle 40 includes an inner conduit 41, a nozzleseat 42 in the form of an open-ended tubular member, said seat 42circumscribing one end 44 of the conduit 41 where the interior 45 of theconduit 41 terminates to form an orifice 46. The other end 47 of theconduit 41 is adapted to be connected to a pressured water supply (notshown) such that water is adapted to flow through the conduit 41 in thedirection of the arrow from end 47 to end 44.

The nozzle 40 also includes, exterior to and coaxial with the conduit41, an outer conduit 48 defining an annular chamber 49 which is adaptedto communicate with a supply of steam pressure (not shown). The outerconduit 48 has an inner wall 50 and an outlet end 51, the end 51disposed downstream from the orifice 46. Coaxially within the outerconduit 48, and downstream from the inner conduit 41, a circumscribingcylindrical shroud 52 is positioned between the end 51 (of the outerconduit 48) and the end 44 (of the inner conduit 41). The tubular shroudmember forms an extension of the inner conduit. (See FIGS. 2 and 3.) Theshroud 52 which defines, between it and the outer conduit 48, thecontinuation of the annular chamber 49, has a shroud orifice 57 at oneend, which is preferably beveled, and at that end, an outwardly disposedcircumferential flange 53, with a depending margin 54 thereabout. Aplurality of serially disposed apertures 55 are drilled through saidflange 53. At the other end of shroud 52 is a flare 56 with a tip 59such that the llare 56 delines with the inner wall 50 (of the outerconduit `48) an outer annular region 61, and with the end 44 (of theconduit 41) an inner annular region 62. An annular spacing member 63spaces the shroud member 52 coaxially from the inner conduit 41. Thespacing member 63 includes a constricting ring 64 that projects radiallyinwardly at the base of the are 56 and defines an aperture of smallerdiameter than that of the interior of the shroud 52 such that when thespacing members 63 is mounted as by welding in the shroud 52, the shroud52, the aperture 64, the inner conduit 41 and the outer conduit 48 arecoaxial. This relationship is maintained by securing the margin 54, asby welding, to the inner wall 50.

Referring to FIG. 3, the nozzle seat 42 comprises an open-ended tubularmember 71 having, at one end, a radially outturned flange 72 and, at theother end, a plurality of circumferential, substantially axiallyextending (slightly skewed) marginal lingers 73 of substantiallytriangular cross-section. The lingers 73 have their ends 74 beveledtoward the axis of the tubular member 71 as do the semi-circular shapedwebs 75 disposed between each nger 73; the apex 76 of each linger 73 isalso disposed toward the axis. The profiles of the lingers, and of thewebs, blend in such a manner that the webs 75 are a terminus of axiallyextending channels 78, slightly skewed, within the inner surface of themember 71, adjacent lingers forming the conlining walls of the channels78.

Within the interior of the member 71, a cylindrical plug 80 is axiallypositionable to control fluid flow running through the interior. Whenthe plug is in full registry (FIG. 4) with the member 71, the channels78 are restricted in cross-sectional area, but still permit a quantityof liow to pass from the nozzle seat 42 into the region of the liare 56.This is more clearly appreciated from FIG. 2, where the plug 80 is shownin its full open position, the shadow lines illustrating the position ofthe plug 80 when in full registry with the member 71.

In operation, a liquid, for example water, flows through the innerconduit 41 and out orilice 46. Because of the slight skew of thechannels 78, this liow is imparted with small angular momentum whichenhances mixing with the gas in the interior of the shroud 52. Gas, forexample steam, llows through the annular chamber 49. At the tip 59 (ofthe liare 56) the steam llow is split into an annular and a core liowpath. The core liow path passes into the inner annular region 62 where alirst mixing begins to take place with the liquid emanating from orilice46. The mixing of the gas and liquid continues as the mixture travelsthrough the interior of the shroud 52. Simultaneously therewith, a partof the steam liow is divided by the tip 59 into the annular liow pathwhich passes through the extension of the annular chamber 49 and outorilices 55 into region 49a where a second mixing takes place betweenthe annular liow path gas issuing from orilices 55 and the rst mixtureof gas and liquid now spouting from the shroud orilice 57. By the timethe mixing fluid reaches further downstream a substantially homogeneoustwo-phase gas-liquid mixture exists.

Examples of satisfactory dimensions for the nozzle 40 are as follows:the gap between the tip 59 and the inner wall 50 (width of the outerannular region 61) is 0.20 inch, while the gap between the tip 59 andthe nozzle seat 42 (the width of the inner annular region 62) is 0.375inch. The inner diameter of the shroud 52 is approximately 13,4 inchesand the width of the extension of the annular chamber 49 (the gapbetween the shroud 52 and the inner wall 50) is approximately 946 inch.The aperture 64 has a diameter of about 11/8 inches. The tencircumferentially, disposed apertures 55 have a diameter of about W11;inch. The plug 80 has a diameter of about 1.024 inches and a length inexcess of 21/2 inches. The channels 78 in the nozzle seat 42 dispose anarea of about 0.035 sq. in. when the plug 80 is in registry, while theorifice 46 displays an area of 0.721 square inch when the plug 80 is notin registry (see FIG. 2). The lingers 73, have their ends 74 beveled atan angle of about 53, while the web 75 is at an angle of about 66, bothangles relatives to the axis of the nozzle seat `42. The channels 78originating at the web 75, and bounded by the ngers 73, are slightlyskewed (about 5 Throughout its length, each channel 78 deviates insuccessive angular increments, as measured relative to the axis of thenozzle seat. Initially each channel deviates, when coincident with theweb 72 at an angle of about 66, then to an angle of about 14 and finallyto an angle of about 83 at which angle the channels intersect andterminate at the outturned llange end of the nozzle seat 42 such thatthe plurality of channels 78 cooperate to form the orice 46.

Using the above example dimensions, the velocity of the liquid particlescan be maintained constant even when the flow is varied from a minimumof 1 unit mass/ unit time (that is approximately 1000 pounds/hour) to amaximum of 10 units mass/unit time (that is 10,000 pounds/hour). This isaccomplished by sliding the plug 80 from the full-closed position to thefull-open position, that is through a stroke of 1.50 inches. Theresulting liquid spray emerges from region 49a with a cone having asmall subtended angle in the neighbourhood of 15.

When the nozzle 40 is used in conjunction with a fog cooling reactor thefuel bundle (not shown) is located downstream from the region 49a about6 inches.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A nozzle for mixing a liquid and a gas comprising, an inner conduitfor connection with a liquid source, a tubular shroud member spaceddownstream from and coaxial with said inner conduit, an outer conduitsurrounding said inner conduit and said shroud member and delining anannular chamber therewith for connection with a gas source, a spacingmember for spacing said shroud member from said inner conduit, saidshroud member having an upstream end and a downstream end, saiddownstream end terminating in an outwardly extending apertured flangeengaged with said outer conduit, said upstream end having a llaredflange extending outwardly upstream to direct a portion of a gas liowingin said annular chamber into said shroud member, a nozzle seat disposedin the downstream end of said inner conduit, said nozzle Seat having aplurality of skewed channels therein to impart angular momentum to aliquid owing therethrough, and a movable plug positionable with respectto said nozzle seat for controlling the liow of liquid.

2. The nozzle according to claim 1 wherein said spacing member includesa constricting ring for constricting the flow of a liuid through theshroud member.

References Cited UNITED STATES PATENTS 218,337 8/1879 Thomas 239-4345 X708,893 9/1902 Lundholm Z39-427.3 982,584 l/l9l1 Frink Z39-417.31,070,872 8/1913 Bond Z39-417.3 1,217,615 2/1917 McDowell 239-427 X2,838,105 6/1958 Eastman et al. 239-423 X SAMUEL F. COLEMAN, PrimaryExaminer Us. c1. XR.

